This invention relates to a clear view cannula for use in surgical procedures. More particularly, this invention relates to a clear view cannula that permits an operator to insert the cannula through a body wall into an anatomical cavity, maintain the cannula in its inserted position, and introduce an auxiliary surgical instrument into the anatomical cavity through the cannula without visual or mechanical obstruction within the body wall.
The use of surgical instruments such as cannulas to introduce an auxiliary surgical instrument into a body such as a joint, abdominal cavity, or the like is well known and widely used. A typical procedure can include making a small incision in the desired portion of the body wall, inserting a cannula into and through the incision and introducing an auxiliary surgical instrument through the cannula into the body to perform a further procedure.
In order to be thoroughly effective and minimize trauma to a patient, it is desirable in such procedures that the cannula be capable of being anchored or secured and not slip out of the anatomical cavity thereby preventing its reinsertion and that fragmented or torn soft tissue not have to be removed from the area surrounding the insertion point of the cannula in order to ensure that the auxiliary instrument can be used without visual or mechanical obstruction.
Several attempts have been proposed to overcome these problems and deficiencies. For example, U.S. Pat. No. 5,217,451 to Freitas discloses a trocar assembly having first and second cylindrical members secured to one another at the distal end of the assembly and a sleeve portion having a series of radially extending flexible members. This device has many small parts and is operable through the use of an interacting gear mechanism. Since the radially extending members, when fully deployed, form an acute angle substantially less than 90 degrees with respect to the longitudinal axis of the cylindrical members, they are not capable of effectively retaining or retracting torn or fragmented soft tissue within a body cavity; that is, the spaces between the fully deployed members permit torn or fragmented soft tissue to visually and mechanically obstruct the use of an instrument such as a camera that is typically introduced through a cannula prior to performing a surgical procedure.
U.S. Pat. No. 5,632,761 to Smith, et.al. discloses a device used to dissect and retract layers of tissue while a portion of the device is retained in a patient. The device utilizes two balloons, the first of which is inserted between layers of tissue and inflated to dissect the tissue layers after which the balloon is deflated. The second balloon is then positioned between the tissue layers and inflated to retract the tissue layers. The device includes a tube coaxially mounted to a delivery portion. The tube has a contracting portion and is provided with a number of deformable, longitudinally extending segments. This device also has many small moving parts and, due to the spherical shape of the second balloon, is not capable of fully retracting torn or fragmented soft tissue. Consequently, the device would have to be inserted deeper into a patient in order to be fully effective.
U.S. Pat. No. 5,637,097 to Yoon discloses an instrument used to penetrate an anatomical cavity having a fixed or retractable penetrating member, the distal end of which is used for penetration, and a portal sleeve having an expandable portion fixed relative to the penetrating member. This instrument, as with the devices described above, comprises many components and functions primarily to anchor the instrument within an anatomical cavity. The anchoring component is not designed to effectively retract or retain torn or fragmented soft tissue within the anatomical cavity.
These illustrative devices typically comprise many parts requiring costly and time consuming assembly. Since they are of relatively complex construction, subsequent cleaning and sterilization would also be costly and time consuming. In addition, these devices are not designed to effectively retract and retain torn or fragmented tissue within an anatomical cavity while, at the same time, anchoring the device within the cavity so that only a minimal portion of the device is retained in the cavity. Due to their complex structures, these devices are cumbersome to handle and manipulate by an operator. Furthermore, these illustrative devices are typically designed to function within a relatively large body cavity such as the abdomen where maneuverability is relatively unrestricted.
It has now been found that the shortcomings of such prior art devices are overcome by the clear view cannula of this invention. In general, the clear view cannula of the invention comprises: a tubular body having a proximate end and a distal end; a plurality of closely spaced teeth members formed on the outer surface and extending parallel to the longitudinal axis of said tubular body intermediate its proximate and distal ends; a cylindrical sleeve having a proximate end and a distal end concentrically mounted about and slidably secured to said tubular body; means at the proximate end of said cylindrical sleeve to engage said teeth members; and, a plurality of spaced apart shield members circumferentially disposed about and longitudinally co-extensive with said tubular body secured to the distal end of said cylindrical sleeve such that when said cylindrical sleeve is slidably urged along said tubular body toward the distal end of said tubular body, said shield members are caused to expand and deploy enabling said shield members to retract and retain torn or fragmented soft tissue within an anatomical cavity and anchor said clear view cannula within an anatomical cavity with a minimum of penetration of said clear view cannula into an anatomical cavity.
The means to secure the cylindrical sleeve to the teeth members as the cylindrical sleeve is slidably moved along the tubular body is readily provided by a detent depending from a raised shoulder at the proximate end of the cylindrical sleeve.
The shield members at the distal end of the cylindrical sleeve and are manufactured so as to be capable of being flexed intermediate their ends enabling them to be fully deployed and expanded within an anatomical cavity.
In one embodiment, the shield members are provided with an expandable web member so that when the shield members are fully deployed, the expandable web member fills the spaces between them thereby further assuring that any torn or fragmented tissue is completely retracted and retained within the body of a cavity.
Although the clear view cannula of the invention can readily be used in large body cavities such as the abdomen, it is particularly useful in smaller cavities such as joints; i.e., knees, shoulders, elbows, ankles, and the like. During arthroscopic surgery of a joint, the joint is typically inflated with water as opposed to a gas which is typically used in abdominal surgical procedures as the surgical procedures performed within a joint are significantly different from those performed within an abdominal cavity.
For example, the inside of a joint such as the knee is lined with a layer of a friable tissue called the synovium which is about xc2xd cm. thick. In patients about to undergo arthroscopic surgery, the synovial tissue is often inflamed and is also frequently torn and fragmented. In addition, there is present in the anterior portion of the knee joint a patella fat pad (or blob of fat tissue) which generally measures about 3xc3x975 cm. square. Thus, inflamed and/or torn and fragmented synovial tissue and the patella fat pad in the knee joint serve to restrict and impede visualization of the joint cavity by the surgeon. However, this restricted vision is completely overcome when using the clear view cannula of the invention.